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NBME 20 Answers

nbme20/Block 3/Question#25

A 4-week-old infant is brought to the emergency ...

Hypertrophic pyloric stenosis

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submitted by hayayah(399),

Most common cause of gastric outlet obstruction in infants. Palpable olive-shaped mass in epigastric region, visible peristaltic waves, and nonbilious projectile vomiting at ∼2–6 weeks old.

Ultrasound shows thickened and lengthened pylorus. Treatment is surgical incision (pyloromyotomy).

katsu  FA 2019 p. 353: Most common cause of gastric outlet obstruction in infants (1:600). Palpable olive-shaped mass in epigastric region, visible peristaltic waves, and nonbilious projectile vomiting at ∼ 2–6 weeks old. More common in firstborn males; associated with exposure to macrolides. Results in hypokalemic hypochloremic metabolic alkalosis (2° to vomiting of gastric acid and subsequent volume contraction). Ultrasound shows thickened and lengthened pylorus. Treatment is surgical incision (pyloromyotomy). +